The limitation of commercially available single-crystal substrates and the lack of continuous strain tunability preclude the ability to take full advantage of strain engineering for further exploring novel properties and exhaustively studying fundamental physics in complex oxides. Here we report an approach for imposing continuously tunable, large epitaxial strain in oxide heterostructures beyond substrate limitations by inserting an interface layer through tailoring its gradual strain relaxation. Taking BiFeO3 as a model system, we demonstrate that the introduction of an ultrathin interface layer allows the creation of a desired strain that can induce phase transition and stabilize a new metastable super-tetragonal phase as well as morphotropic phase boundaries overcoming substrate limitations. Furthermore, continuously tunable strain from tension to compression can be generated by precisely adjusting the thickness of the interface layer, leading to the first achievement of continuous O-R-T phase transition in BiFeO3 on a single substrate. This proposed route could be extended to other oxide heterostructures, providing a platform for creating exotic phases and emergent phenomena.
@article{arxiv.1905.01070,
title = {Strain engineering of epitaxial oxide heterostructures beyond substrate limitations},
author = {Xiong Deng and Chao Chen and Deyang Chen and Xiangbin Cai and Xiaozhe Yin and Chao Xu and Fei Sun and Caiwen Li and Yan Li and Han Xu and Mao Ye and Guo Tian and Zhen Fan and Zhipeng Hou and Minghui Qin and Yu Chen and Zhenlin Luo and Xubing Lu and Guofu Zhou and Lang Chen and Ning Wang and Ye Zhu and Xingsen Gao and Jun-Ming Liu},
journal= {arXiv preprint arXiv:1905.01070},
year = {2025}
}